One of the major problems facing the fruit, vegetable and cut flower industry is the loss of a considerable amount of goods due to spoilage. It is estimated that 12 to 20 percent of the fruit and vegetable products become spoiled from the time they leave the farm until they get to the retail or processing outlets. In the cut flower industry, senescence (the wilting or dying) of the flower before it can be effectively marketed is a significant problem. The spoiling or senescence process observed in fruits, vegetables and cut flowers results in a number of undesirable problems. Chief among these problems is the short harvesting season for the goods and the short shelf life of the goods following the harvest. Furthermore, these spoilage losses ultimately result in a higher cost of the goods to the consumer.
A primary cause of the spoilage of fruits and vegetables is the natural ripening process of the fruit or vegetable. As the fruit or vegetable becomes more ripe it becomes softer and more easily bruised and susceptible to disease or other spoilage causing agents. It is known that ethylene production in the plant stimulates the fruit ripening process and is the key component in the ripening of fruits and vegetables. Others have attempted to control the ripening of fruits and vegetables in an attempt to extend the shelf life and/or harvesting season of the goods. Many of these attempts have been topical applications of chemicals to the fruit or vegetable itself. These chemical solutions have involved direct applications to the plant in the field or post-harvest applications to the fruit or vegetable itself. Several of these methods are discussed in U.S. Pat. No. 4,957,757 or U.S. Pat. No. 4,851,035. Due to the increasing importance of reducing additional stresses on the environment, a non-chemical means for controlling ripening would be advantageous and beneficial to the industry.
More recently, researchers have used a molecular biology approach to block ethylene synthesis in plants in an attempt to control the ripening of tomatoes. This approach involved transforming a tomato plant with an antisense gene that inhibited the synthesis of ethylene. The antisense gene produces (-) strand RNA that lowers the steady state levels of the (+) strand mRNA encoding a polypeptide involved in the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by the ethylene forming enzyme ACC oxidase. (Hamilton et al. 1990) While this method exhibits some degree of utility, it would be neither easy nor efficient to apply this technology to other plants, because the antisense gene would probably be species and gene specific which would entail obtaining a different antisense gene for each species of plant desired to be transformed.
Thus a need exists in the fruit, vegetable and cut flower industries for a non-chemical method of controlling fruit ripening and senescence in plants that can easily and efficiently be utilized across a wide variety of plant species.